Abstract :
[en] Due to its small size, its short developmental cycle and its close phylogenetic relationship with the Triticeae tribe, Brachypodium distachyon (L.) Beauv. has been proposed as a model species for temperate cereals. In this context, this work aims to describe and model root and shoot growth and development of B. distachyon (Bd21-1) grown under controlled environmental conditions [22°C, 65% RH, 20h light, 95 µmol.m-2.s-1 (PAR, LED lighting)]. For this purpose, vernalized caryopses were sown in a substrate consisting of vermiculite and compost (80/20, v/v). Growth and development of the above and belowground parts were monitored for 70 days. Dry and fresh masses of plant organs were measured every seven days from sowing. Biomasses of adventitious and seminal roots were measured separately. The number of spikelets on the main stem and on tillers was also counted on plants aged of 70 days.
The modelling of root and shoot growth was achieved by calibrating sigmoidal growth models to the mean biomass values measured at each day of analysis. For each plant organ, the growth model selected was the one with the lowest residual variance. Finally, developmental stages identified for B. distachyon were compared with those defined for cereal crops by Zadoks et al. (1974).
Maximum rates of fresh and dry shoot biomass production were 29,5 and 14,2 mg.day-1 respectively. Based on modelling, these values seem to be reached 49 and 72 days after sowing. Results also show that the fresh mass of adventitious roots at day 42 is significantly higher than that of seminal roots. Maximum rates of fresh and dry root biomass production were 6,9 and 0,8 mg.day-1 respectively, and were reached after 37 and 43 days.
